Fix: return failure when PhoneAPI times out (#3136)

* Add debug options for RP2040

* Rename: "observed" should be plural: "observables"

* PhoneAPI: return failure on timeout
In `onNotify()`, when disconnected, PhoneAPI removed itself from the list of observers that was looped through in `notifyObservers()`. We should exit that loop in that case.

src/mesh/PhoneAPI.h

@@ -108,8 +108,8 @@ class PhoneAPI
     /// Hookable to find out when connection changes
     virtual void onConnectionChanged(bool connected) {}
 
-    /// If we haven't heard from the other side in a while then say not connected
-    void checkConnectionTimeout();
+    /// If we haven't heard from the other side in a while then say not connected. Returns true if timeout occurred
+    bool checkConnectionTimeout();
 
     /// Check the current underlying physical link to see if the client is currently connected
     virtual bool checkIsConnected() = 0;
@@ -142,4 +142,4 @@ class PhoneAPI
 
     /// If the mesh service tells us fromNum has changed, tell the phone
     virtual int onNotify(uint32_t newValue) override;
-};
+};